The invention relates to wire advancing arrangements for electric arc-welding applications, and more particularly to adjustable-force arrangements of this type employing planetary rollers for advancing the wire.
In one known system of this type for feeding an electrode wire forwardly along a first axis and into the arc-welding arrangement, a pair of skewed rollers are individually carried by a pair of pistons that are reciprocated radially in a feed housing on opposite sides of the axis. When the pistons are in their innermost position, the rollers cooperate to engage the wire in screw thread-like fashion so that, upon a rotation of a drive motor shaft coupled to the feed housing, the skewed rollers rotate in planetary fashion as the housing revolves on its axis to advance the thread. In order to permit adjustable of the force applied to the wire by the rollers as a function of the wire diameter and/or the load to which the wire is subjected by the arc-welding facilities during advance, an adjustable threaded nut or the like is provided for engagement with a threaded rear portion of the main housing. The adjustment nut is dynamically coupled to at least one of the pistons to adjust the force of the rollers on the engaged wire.
A disadvantage of such designs is that the force adjustment (e.g., by turning the threaded nut) is done manually and for each setting is only suitable for a narrow range of wire diameters and loads.